Route monitoring system and method

ABSTRACT

A monitoring method and system monitor a transmitted current that is injected into conductive components of a route traveled by vehicle systems, monitor a received current that represents a portion of the transmitted current that is conducted through the conductive components of the route, examine changes in the transmitted and/or received current over time to determine when the vehicle systems are on the route between a first location where the transmitted current is injected into the conductive components and a second location where the received current is monitored, and examine the changes in the transmitted and/or received currents. The changes are examined to identify (a) a contaminated portion of a surface on which the route is disposed, (b) a foreign object other than the vehicle systems that is contacting the route, and/or (c) a damaged or broken portion of at least one of the conductive components of the route.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 15/345,158, which was filed on 7 Nov. 2016, and which is acontinuation of U.S. patent application Ser. No. 14/512,729, which wasfiled on 13 Oct. 2014.

U.S. patent application Ser. No. 14/512,729 claims priority to U.S.Provisional Application No. 61/912,069, which was filed on 5 Dec. 2013.

The entire disclosures of all these applications are incorporated hereinby reference.

FIELD

Embodiments of the inventive subject matter described herein relate toelectrically monitoring a route traveled by one or more vehicle systems.

BACKGROUND

Some wayside monitoring systems monitor electric current that isconducted in rails of a track to determine when rail vehicles travel oncertain segments of the track. When a rail vehicle travels on thesegment of the track through which current is being conducted, the railvehicle can short out a circuit that includes the rails of the track.This shorting of the circuit can be detected so that the presence of therail vehicle on the track can be automatically detected.

These systems rely on assumptions that no external factors otherwiseimpact the conduction of current through the rails of the track. Forexample, if another foreign object or body creates or forms a short orshunt in the circuit that includes the rails of the track, the waysidemonitoring system that is monitoring that segment of the track mayincorrectly determine that a rail vehicle is on the segment of thetrack. This incorrect determination can result in disruption of the flowof traffic in a transportation network that includes the track.

For example, after incorrectly identifying a segment of the track asbeing occupied by a rail vehicle, the wayside monitoring system mayautomatically change a traffic or warning signal to erroneously indicateto other rail vehicles that the segment of the track is occupied.Additionally or alternatively, the wayside monitoring system mayincorrectly notify a dispatch center that the segment of the track isoccupied, which can prevent the dispatch center from using that segmentof the track to route rail vehicles.

The erroneous identification of a rail vehicle on the segment of trackmay only be identified by an operator after an extended period of time.Then, one or more persons may be required to travel to the route segmentand visually inspect the segment of track to identify the cause of theerrors by the wayside monitoring system. The wayside monitoring systemmay be unable to identify any potential cause for the errors to thepersons seeking to repair the problem with the track.

BRIEF DESCRIPTION

In one embodiment, a monitoring method includes monitoring a transmittedcurrent that is injected into conductive components of a route that istraveled by one or more vehicle systems, monitoring a received currentthat represents at least a portion of the transmitted current that isconducted through the conductive components of the route, examiningchanges in one or more of the transmitted current or the receivedcurrent over time to determine when at least one of the vehicle systemsis disposed on the route between a first location along the route wherethe transmitted current is injected into the conductive components and adifferent, second location along the route where the received current ismonitored, and examining the same changes in the one or more of thetransmitted current or the received current to identify at least one ofa contaminated portion of a surface on which the conductive componentsof the route are disposed, to identify a foreign object other than theone or more vehicle systems that is contacting the conductive componentsof the route, or to identify a damaged or broken portion of at least oneof the conductive components of the route.

In another embodiment, a monitoring system includes a transmit monitorand a receive monitor. The transmit monitor includes one or moreprocessors configured to measure a transmitted current that is injectedinto conductive components of a route that is traveled by one or morevehicle systems. The receive monitor includes one or more processors(which may be one or more of the same processors as the transmit monitoror different processors than the transmit monitor) that are configuredto measure a received current that represents at least a portion of thetransmitted current that is conducted through the conductive componentsof the route. At least one of the transmit monitor or the receivemonitor also is configured to examine changes in one or more of thetransmitted current or the received current over time to determine whenat least one of the vehicle systems is disposed on the route between afirst location along the route where the transmitted current is injectedinto the conductive components and a different, second location alongthe route where the received current is monitored. At least one of thetransmit monitor or the receive monitor is configured to examine thesame changes in the one or more of the transmitted current or thereceived current to identify at least one of a contaminated portion of asurface on which the conductive components of the route are disposed, toidentify a foreign object other than the one or more vehicle systemsthat is contacting the conductive components of the route, or toidentify a damaged or broken portion of at least one of the conductivecomponents of the route.

In another embodiment, a monitoring method includes measuring atransmitted current that is applied at a first location to conductiverails of a track over which one or more rail vehicles travel andmeasuring a received current at a different, second location to theconductive rails of the track. The received current includes at least aportion of the transmitted current that is conducted through one or moreof the conductive rails from the first location to the second location.The method also can include identifying changes in the transmittedcurrent and in the received current over time in order to both identifywhen the one or more of the rail vehicles travel between the firstlocation and the second location and when at least one of: ballastmaterial disposed between the conductive rails becomes contaminated toat least partially form a short between the conductive rails, a foreignobject other than the one or more rail vehicles forms the short betweenthe conductive rails, or one or more of the conductive rails is damagedor broken between the first location and the second location.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference is now made briefly to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a monitoring system in accordance withone aspect of the inventive subject matter described herein;

FIG. 2 illustrates another schematic diagram of the monitoring systemshown in FIG. 1;

FIG. 3 illustrates changes in a transmitted current that is injectedinto conductive components of a route shown in FIG. 1 and changes in areceived current that is conducted by the conductive components of theroute when a vehicle system travels along the route;

FIG. 4 illustrates examples of changes in the transmitted current andchanges in the received current when ballast material on which the routeis positioned becomes contaminated;

FIG. 5 illustrates examples of changes in the transmitted current and inthe received current when a foreign object extends across the conductivecomponents of the route;

FIG. 6 illustrates examples of changes in the transmitted current and inthe received current when one or more of the conductive components ofthe route are damaged or broken;

FIG. 7 is another schematic illustration of the monitoring system shownin FIG. 1;

FIG. 8 illustrates transmitted and received currents that are measuredby several monitoring systems connected with different segments of thesame route in accordance with one embodiment;

FIGS. 9A and 9B illustrate a flowchart of a method for monitoring asegment of a route in accordance with one embodiment of the inventivesubject matter; and

FIG. 10 is a schematic diagram of another monitoring system.

DETAILED DESCRIPTION

One or more embodiments of the inventive subject matter described hereinprovide monitoring systems and methods that monitor electricalcharacteristics of a segment of a route on which one or more vehiclesmay travel. The electrical characteristics are monitored in order todetect the presence of a vehicle system (e.g., a single vehicle, or twoor more vehicles mechanically coupled together to travel together alongthe route, such as in a consist) on the route segment. For example, theroute may include plural conductive components (e.g., rails) and thevehicle system may include wheels connected by axles that, when thewheels contact the conductive components of the route, form a conductivepathway or bridge between the conductive components of the route. Thesystems and methods described herein can monitor changes in electricalcharacteristics of the conductive components of the route (e.g., changesin an electric current transmitted and received along the conductivecomponents of the route) in order to detect the presence (or absence) ofthe vehicle system on the route.

Additionally, the systems and methods can examine the electriccharacteristics over time to identify trends or other changes in thecharacteristics that may be emblematic of one or more problems with theroute. For example, significant increases in an electric current that isinjected into the conductive components of the route (which also can bereferred to as a transmitted current) and/or significant decreases in anelectric current that is received from the conductive components of theroute (which also can be referred to as a received current) over anextended period of time can signify that the surface or materials onwhich the conductive components of the route are positioned (e.g.,ballast material) has become contaminated or otherwise damaged (and mayneed cleaning or replacing). Additionally or alternatively, the systemsand methods can determine that the conductive components of the routehave been shorted out (e.g., coupled by a conductive pathway other thana vehicle system) based on rapid and significant changes in thetransmitted current, the received current, or both the transmittedcurrent and the received current. Optionally, the systems and methodscan determine that one or more of the conductive components of the routeare damaged (e.g., broken) based on rapid and significant changes in thetransmitted current, the received current, or both the transmittedcurrent and the received current.

Once the systems and methods have identified the problems with thesurface on which the conductive components of the route are positionedand/or with the conductive components themselves, the systems andmethods can take one or more remedial actions. For example, signals canbe communicated to one or more locations to request servicing or repairof the surface and/or conductive components of the route, to requestmodification of an electronic circuit that includes the conductivecomponents of the route, to automatically warn approaching vehiclesystems of problems with the surface and/or conductive components of theroute, and the like.

One embodiment provides a system and method that measure track circuitparameters at transmit and receive ends of a track circuit that includesconductive rails of a track. The system and method analyze short termand long term trends of the parameters (e.g., current, resistance,voltage, or the like) in order to predict imminent failures of the trackcircuit so that maintenance is forced or automatically requested tointervene prior to the failure and, when there is a failure, the systemand method can identify a type of failure to optimize (e.g., reduce) thecost and timeliness of the response of maintenance to repair thefailure.

The system and method can monitor and sample electrical current on thetrack circuit at each end of the circuit. The sampled values areperiodically transmitted to an analysis subsystem (e.g., a transmitmonitor, a receive monitor, or both), either wayside on the railway orcommunicated to a central office. The analysis subsystem identifiestrends in the parameters and yields decisions on whether the circuit isperforming within bounds or needs maintenance. In an example embodiment,receive current parameters may trend downward during rain, as the trackballast becomes wet and more electrically conductive. Over time,typically in months or years, as ballast stone becomes contaminated withdirt, the dip in receive current when wet becomes more pronounced. Whenthe sampled current meets an alarm threshold (e.g., determined by alearning algorithm or calculated), the risk of a false occupancy of thetrack circuit increases. The alarm threshold can be set to allow amaintainer to intervene and adjust the circuit before the failureoccurs. For example, instead of setting a threshold at a value at whichthe circuit would incorrectly identify a segment of the track as beingoccupied, the threshold may be moved downward or upward (as appropriate)so that the contaminated ballast may be identified before the trackcircuit begins incorrectly determining that the track circuit isoccupied by a vehicle system. Over more time, this margin for adjustmentwill be depleted, and the system or method will determine that theballast stone needs to be cleaned or refreshed.

In another example, an actual track circuit failure can occur, and thesystem and method can identify the type of failure, such as a shortcircuit on the track (e.g., due to scrap metal, failed switch rodinsulation, or the like) or a load on the track due to fouled and or wetballast conditions outside of a current adjustment range (e.g.,additional resistive elements cannot be added to the track circuit toreduce the trends in the current, as described below). Depending on thetype of failure, the appropriate number of maintainers can beautomatically requested or dispatched more efficiently correct theproblem.

The erroneous identification of track occupancies can cause railwaysignals to go red (e.g., stop), which disrupts traffic flow, as well ascause unplanned maintenance expenses. One or more embodiments of thesystems and methods described herein predict necessary maintenance forlow ballast condition failures, allowing adjustment of the track circuitbefore failures. If the cause of a failure is determined to be a shortcircuit, multiple maintainers can be dispatched to walk the trackcircuit to clear the cause of the failure (e.g., remove scrap metal froma train from the track). If the system or method determines a failure tobe due to fouled ballast, only one maintainer may need to be dispatchedto make adjustments to the track circuit.

FIG. 1 is a schematic diagram of a wayside monitoring system 100 inaccordance with one aspect of the inventive subject matter describedherein. The monitoring system includes or represents one or morehardware circuits or circuitry that includes and/or is coupled with oneor more processors, controllers, or other electronic logic-based devicesthat operate to perform various operations described herein. Themonitoring system is coupled with a route 102 on which vehicle systems104 travel along. The route 102 is positioned on a surface 110 formedfrom one or more materials 112. These materials can be referred to asballast material, and can include (by way of example only), rock, dirt,or other types of materials. Optionally, the surface and materials mayrepresent another surface that does not include ballast material.Although only a single vehicle system is shown, multiple vehicle systemsmay concurrently travel along the route. Additionally, the vehiclesystem 104 is shown as including a single vehicle, but optionally mayinclude multiple vehicles mechanically coupled with each other to traveltogether along the route, such as in a consist. For example, one or moreembodiments of the monitoring system and method described herein may beused in conjunction with a rail vehicle (e.g., rail vehicle consist,train, locomotive, or the like) that travels along a track (e.g., theroute). Optionally, the monitoring system and/or method may be used inconjunction with one or more other types of vehicles and/or routes. Forexample, the vehicle system may be formed from two or more vehicles thattravel together along routes, but that are not mechanically coupled witheach other. These vehicles can be logically coupled and/orcommunicatively coupled without being mechanically connected with eachother, yet travel together along routes as a vehicle system. Thesevehicles can communicate with each other to coordinate relativemovements of each vehicle with each other so that the separate vehiclesmove together (e.g., as a convoy) along routes as a vehicle system.

The monitoring system 100 is coupled with the route 102 at two or morespaced apart locations 106, 108. Alternatively, the monitoring system100 may be coupled with the route 102 in a single location. In theillustrated example, one location may be referred to as a transmittinglocation while the other location may be referred to as a receivinglocation. The monitoring system may be coupled with the route so thatthe monitoring system can inject electric signals (e.g., electriccurrents that are controlled by the monitoring system) into the route atthe transmitting location. The monitoring system also may be coupledwith the route so that the monitoring system can receive electricsignals (e.g., the electric current that is injected into the route atthe transmitting location and that is conducted along the route) at thereceiving location. For example, the monitoring system may beconductively and/or inductively coupled with the route at thetransmitting and receiving locations.

The monitoring system 100 injects the electric signals into the route102 at the transmitting location 106 or 108 by applying an electriccurrent that is controlled by the monitoring system (e.g., the phase,amplitude, frequency, and the like, is controlled by the monitoringsystem) to route, such as to the rails of a track. This current can bereferred to as a transmitting or transmitted current. The monitoringsystem can measure the electric current that is conducted along theroute at the receiving location 108 or 106. This current can be referredto as a receiving, received, sensed, or measured current. Based onchanges in the transmitted current, changes in the received current,and/or differences between the transmitted and received currents, themonitoring system can determine if the vehicle system 104 is travelingalong the route between the transmitting and receiving locations alongthe route. Additionally, the monitoring system can track changes in thetransmitted current and/or changes in the received current over time inorder to identify and/or predict damage to the route, as describedbelow.

FIG. 2 illustrates another schematic diagram of the wayside monitoringsystem 100 shown in FIG. 1. In the illustration shown in FIG. 2, theroute 102 is shown from a top view so plural conductive components orportions 200, 202 (e.g., rails) of the route 102 are visible.Additionally, the vehicle system 104 is shown in phantom view so thatwheels 204 and axles 206 of the vehicle system are visible. The waysidemonitoring system can be coupled with the conductive components in thetransmitting and receiving locations 106, 108. The wayside monitoringsystem can be coupled with or include a source of electric energy (e.g.,a power source) that applies current to the conductive components at thetransmitting location 106. For example, the power source and/ormonitoring system can be conductively coupled with the conductivecomponent 200 of the route at a positive terminal 208 and with theconductive component 202 of the route at a negative terminal 210. Thetransmitted current can be applied to the conductive components acrossthe positive and negative terminal. The monitoring system similarly canbe conductively coupled with the conductive components in the receivinglocation 108 at corresponding first and second terminals 212, 214.

With continued reference to the wayside monitoring system 100 shown inFIGS. 1 and 2, FIG. 3 illustrates changes in a transmitted current 300that is injected into the conductive components of the route at thetransmitting location 106 along the route 102 and changes in a receivedcurrent 302 that is sensed by the monitoring system at the receivinglocation 108 along the route when the vehicle system 104 travels acrossthe route. The transmitted and received currents are shown alongside ahorizontal axis 304 representative of time (e.g., in terms of minutes orhours) and a vertical axis 306 representative of a magnitude of thetransmitted and received currents. For example, the vertical axis canrepresent different amps of the transmitted and received currents,voltages of the transmitted and received currents (e.g., where thecurrents are direct currents), or other measurements of the transmittedand received currents.

Prior to entry of the vehicle system 104 onto a segment 216 of the route102 that is between the transmitting and receiving locations 106, 108(referred to herein as a route segment under examination or a monitoredroute segment), the monitoring system 100 may apply the transmittingcurrent 300 to the conductive components 200, 202 of the route in thetransmitting location at a first magnitude 308. Due to resistance of theconductive components between the transmitting location and thereceiving location, the received current 302 may be sensed by themonitoring location at a smaller, second magnitude 310.

When the vehicle system 104 enters into the examined segment 216 of theroute 102 at a time of entry 316, the vehicle system may change one ormore of the transmitted and/or received currents 300, 302. For example,the wheels 204 connected to an axle 206 may form a conductive pathwaybetween the conductive components 200, 202 of the route between thetransmitting and receiving locations 106, 108. This conductive pathwaycan form a lower resistance pathway for the transmitted current 300 totravel along in an electronic circuit that includes the conductivecomponents. For example, the wheels and axles can short out theelectronic circuit that includes the power source that supplies thetransmitted current, the conductive components of the route, and themonitoring system. The short or shunt created by the wheels and axlescan result in the transmitted current increasing to a larger, thirdmagnitude 312 due to the decrease in resistance in the circuit caused bythe short. For example, the power supply may supply approximately thesame voltage (e.g., by direct current or a time-varying voltage that isan alternating current) to the conductive components at the transmittinglocation, and the lower resistance of the circuit causes thetransmitting current to increase while the applied voltage remains thesame or substantially the same. The short or shunt created by the wheelsand axles can result in the received current 302 decreasing to asmaller, fourth magnitude 314 due to the decrease in transmitted currentthat is conducted in the circuit to the receiving location. For example,more of the transmitted current may not reach the receiving location dueto the short created by the vehicle system.

When the vehicle system 104 exits the examined segment 216 of the route102 at a time of exit 318, the short created by the vehicle system is nolonger present in the circuit that includes the conductive components200, 202 of the route. As a result, the transmitted current 300 maydecrease back to the first magnitude 308 (e.g., due to the increasedresistance of the circuit without the short) and the received current302 may increase back to the second magnitude 310 (e.g., due to more ofthe transmitted current being conducted to the receiving location 108when the short is no longer present). The monitoring system 100 canexamine the transmitted and/or received currents in order to determinewhen the examined segment is occupied by the vehicle system.

The time period over which the vehicle system 104 travels over theexamined segment 216 of the route 102 (e.g., the time between the timeof entry 316 and time of exit 318) can be relatively short, such as onthe order of a few minutes or hours. In accordance with one or moreaspects of the inventive subject matter described herein, the monitoringsystem 100 may additionally or alternatively monitor the transmittedand/or received currents 300, 302 over longer periods of time in orderto identify and/or predict potential contamination or damage to theroute and/or the surface 110 on which the route is positioned. Forexample, changes in the transmitted and/or received currents overextended periods of time may indicate that the ballast material on whichthe route is disposed may need to be cleaned and/or replaced, that theroute is damaged (e.g., one or more of the conductive components isbroken), that a foreign object is on the route, and the like.

As one example, the ballast material 112 on which the conductivecomponents 200, 202 of the route 102 are disposed may becomecontaminated, such as with materials carried by the vehicle systems thatdrip or fall onto the ballast material, the ballast material corroding,the ballast material freezing or becoming at least partially submergedin water, or the like. This contamination may cause at least acontaminated portion 218 of the ballast material to increase inconductivity (or otherwise decrease in resistance). For example, theportion of the ballast material that is contaminated may be coupled withthe conductive components such that this portion of the ballast materialforms a pathway between the conductive components that has a lowerresistance that other portions of the ballast material. As a result, atleast some of the transmitted current 300 that is injected into theconductive components may be conducted between the conductive componentsby the contaminated portion of the ballast material and not be sensed aspart of the receiving current 302 at the receiving location 108. Ifenough current is conducted by the contaminated portion of the ballastmaterial, the monitoring system 100 may erroneously determine that avehicle system is present in the examined segment 216 of the route.

As another example, a portion 220 of one or more of the conductivecomponents 200, 202 of the route 102 may become damaged (e.g., brokenthrough an entire cross-sectional area of the component or through asignificant portion of the cross-sectional area). This damage can reducethe amount of transmitted current 300 that is sensed at the receivinglocation 108 of the route as the receiving current 302. If enoughcurrent is unable to be conducted through the damaged portion 220 of theroute, then the monitoring system 100 may be unable to determine that avehicle system 104 is located within the examined section or segment 216of the route when the vehicle system is present in the examined sectionof the route.

As another example, a foreign object may be positioned on the route 102between the conductive components 200, 202 of the route. For example, achain, bar, pipe, bicycle, or other at least partially conductive objectmay fall onto the route so that the object engages both of theconductive components of the route within the examined section 216 ofthe route. The contaminated portion 218 of the ballast material 212shown in FIG. 2 alternatively may represent such an object. If thisobject has sufficient conductivity, the object can form a pathwaybetween the conductive components that has a lower resistance than theconductive components between the transmitting and receiving locations106, 108. As a result, at least some of the transmitted current 300 thatis injected into the conductive components may be conducted between theconductive components by the foreign object and not be sensed as part ofthe receiving current 302 at the receiving location 108. If enoughcurrent is conducted by the foreign object, the monitoring system 100may erroneously determine that a vehicle system is present in theexamined segment 216 of the route.

The above are just a few non-limiting examples of external factors(e.g., causes other than the presence of the vehicle system 104 in theexamined segment 216 of the route 102) that can change the conductivityof a circuit that includes the conductive components 200, 202 of theroute between the transmitting and receiving locations 106, 108. Inorder to prevent any such change in the conductivity of the circuit fromerroneously causing the monitoring system 100 from correctly identifyingthe presence or absence of the vehicle system in the examined segment ofthe route, the monitoring system may examine changes in the transmittedand/or received currents 300, 302 over time in order to predict oridentify these external factors modifying the transmitted and/orreceived currents.

FIG. 4 illustrates examples of changes in the transmitted current 300that is injected into the conductive components of the route at thetransmitting location 106 along the route 102 and changes in thereceived current 302 that is sensed by the monitoring system at thereceiving location 108 along the route when the ballast material 112 onwhich the route is positioned becomes contaminated. The transmitted andreceived currents are shown alongside a horizontal axis 400representative of time and a vertical axis 402 representative ofmagnitudes of the transmitted and received currents 302, 304. Thehorizontal axis shown in FIG. 4 differs from the horizontal axis 304shown in FIG. 3 in that the horizontal axis of FIG. 4 represents a muchlonger time period. For example, the horizontal axis in FIG. 3 mayrepresent time periods of several minutes to few hours, while thehorizontal axis in FIG. 4 can represent time periods extending overseveral days, weeks, months, or years. The vertical axis shown in FIG. 4may be different from the vertical axis 306 shown in FIG. 3 in that thevertical axis of FIG. 4 may encompass much smaller and larger magnitudesof the transmitting and/or receiving currents.

The transmitted and received currents 300, 302 shown in FIG. 4 may besampled by the monitoring system 100 at various times. For example,instead of continuously measuring the transmitted and received currents,the monitoring system may measure the transmitted and/or receivedcurrents periodically (e.g., once every second, every few seconds, everyfew minutes, every few hours, every few days, or the like) or whendirected by an operator or other external event (e.g., a vehicle systemleaving the examined segment of the route). Alternatively, thetransmitted and/or received currents may be continuously measured by themonitoring system.

As shown in FIG. 4, the transmitted current 300 gradually increases overtime from a first magnitude 404 and the received current 302 graduallydecreases over time from a second magnitude 406. The first and secondmagnitudes shown in FIG. 4 may correspond to the corresponding first andsecond magnitudes 308, 310 shown in FIG. 3. The increases in thetransmitted current and/or the decreases in the received current overthe extended time period shown in FIG. 4 can be identified by themonitoring system 100 (shown in FIG. 1) as being caused by an externalfactor other than the presence of a vehicle system 104 (shown in FIG.1).

The monitoring system 100 can distinguish between relatively rapid ratesof change in the transmitting and/or receiving currents 300, 302 andmore gradual (e.g., slower) rates of change in the transmitting and/orreceiving currents. As shown in FIG. 4, both the transmitting currentand the receiving current exhibit faster rates of change (e.g.,corresponding increases or decreases) during three corresponding timeperiods 408, 410, 412, but slower overall rates of change between thesetime periods. The transmitting current increases from the initial firstmagnitude 404 to an upper threshold magnitude 414 while the receivingcurrent decreases from the initial second magnitude 406 to a lowerthreshold magnitude 416.

The monitoring system 100 can ignore the faster rates of change duringthe time periods 408, 410, 412 but identify the larger changes in thetransmitting and receiving currents 300, 302 to the correspondingthreshold magnitudes 414, 416 as indicative of the ballast material 112(shown in FIG. 1) becoming contaminated. For example, if the monitoringsystem identifies an increase in the transmitting current to the upperthreshold magnitude 414 and/or a decrease in the receiving current tothe lower threshold magnitude 416, and this increase or decrease occursover a relatively long threshold time period (e.g., a time period thatis longer than the time period of inclement weather, a vehicle systemtraveling over the examined segment of the route, or the like, such asseveral days, weeks, or months), then the monitoring system can identifythe increase or decrease as being indicative of a contaminated portion218 of the ballast material, as shown in FIG. 2. The smaller and/or morerapid rates of change in the transmitting and/or receiving currents canbe caused by a variety of temporary external factors, such as wetweather conditions (e.g., the ballast material 112 becomes wet or frozenbetween the conductive components 200, 202 of the route 102). But,because these temporary factors generally do not extend or continue onfor the length of time period over which the monitoring system monitorsthe transmitting and/or receiving currents, the monitoring system candistinguish between temporary changes in the transmitting and/orreceiving currents and longer term changes in the transmitting and/orreceiving currents.

In one aspect, a temporary change may occur when the transmitting and/orreceiving currents vary in value (e.g., magnitude, frequency, or thelike) for a time period that is no greater than a designated time period(e.g., one second, five seconds, ten seconds, one minute, five minutes,ten minutes, or another value). Changes in the currents that last atleast as long as this designated time period may not be temporarychanges in the currents. The length of the designated time period may beadjusted to control the sensitivity of the monitoring system.

The upper and/or lower thresholds may be learned over time. For example,when one examined segment of the route is later identified as havingcontaminated ballast that is conducting current between the conductivecomponents of the route, the transmitted and/or received currents atwhich the ballast material is identified as being contaminated may berecorded. This same procedure may be repeated for several segments ofone or more routes. The recorded values may be referred to as failurevalues. An average, median, or other calculation of these values may beused as one or more of the upper and/or lower thresholds. As additionalsegments have ballast material that becomes contaminated, thesethresholds may be updated.

Additionally or alternatively, the weather conditions at or near themonitoring system 100 may be taken into account when examining thetransmitted and/or received currents. For example, during wet weather(e.g., rain, snow, sleet, or the like), the resistance of the circuitthat includes the conductive components 200, 202 of the route 102 maydecrease and/or one or more shorts may form in the ballast material 112between these conductive components 200, 202 (e.g., by pools of moisturein the ballast material). The system 100 may ignore changes in thetransmitted current and/or received current during such weatherconditions, as these changes may not be indicative of longer termchanges or contamination of the ballast material 112.

The monitoring system 100 can determine that at least a portion of theballast material 112 that contacts the conductive components 200, 202 ofthe route 102 is at least partially conducting the transmitted current300 between the conductive components when the transmitted currentincreases and/or the received current decreases over a time period thatis longer than a time period during which a vehicle system 104 travelsor would travel over the route 102 from the transmitting location 106 tothe receiving location 108 (or from the receiving location to thetransmitting location). The time period during which the vehicle systemtravels or would travel over this length of the route can be calculatedbased on the distance between the transmitting and receiving locationsand a designated speed of the vehicle system. The designated speed canbe a lower speed limit of the route in the examined section 216, such asa minimum speed that the vehicle system is required to travel accordingto rule, regulation, law, or otherwise.

For example, if the distance between the transmitting location and thereceiving location is two miles (e.g., 3.2 kilometers) and the lowerspeed limit of the route in this segment is twenty miles per hour (e.g.,32 kilometers per hour), then the time period over which a vehiclesystem should travel over this examined segment or is expected to travelover the examined segment is six minutes. If the monitoring systemdetermines that the transmitted current continues to increase over alonger time period and/or that the received current continues todecrease over a longer time period, then the monitoring system candetermine that a portion of the ballast material between the conductivecomponents of the route is at least partially conducting electriccurrent between the conductive components (e.g., is forming a short or ashunt).

The monitoring system can ignore temporary smaller and/or more rapidrates of change in the currents 300, 302, such as the increases ordecreases during the time periods 408, 410, 412. These changes can beignored by the monitoring system because the corresponding increase ordecrease in magnitude of the transmitting and/or receiving current isnot sufficiently large to exceed the corresponding upper or lowerthreshold 414, 416, and/or because the rate of change in the currents isfaster than a threshold rate of change. For example, even if thetransmitting current increases above the upper threshold magnitudeand/or the receiving current falls below the lower threshold magnitude,if the increase or decrease in the corresponding current occurs over tooshort of a time period (e.g., less than a threshold time period), thenthe monitoring system can disregard the change as being caused by atemporary condition, such as the weather. Increases and/or decreases inthe transmitting and/or receiving currents above or below the thresholdmagnitudes 414, 416 can be identified by the monitoring system as beingcaused by a contaminated portion 218 (shown in FIG. 2) of the ballastmaterial 112 (also shown in FIG. 2) when the increases and/or decreasesoccur over a longer period of time, such as a threshold period of time418. Additionally or alternatively, the weather conditions at themonitoring system 100 can be monitored to determine if the temporarychanges in the transmitted and/or received currents are at leastpartially caused by shorts formed from rain, snow, sleet, or the like,between the conductive components of the route.

FIG. 5 illustrates examples of changes in the transmitted current 300that is injected into the conductive components of the route at thetransmitting location 106 along the route 102 and changes in thereceived current 302 that is sensed by the monitoring system at thereceiving location 108 along the route when a foreign object extendsacross the conductive components 200, 202 of the route. The transmittedand received currents are shown alongside the horizontal axis 304 andthe vertical axis 306 described above. The transmitted and receivedcurrents may be sampled by the monitoring system at various times,similar to as described above. Alternatively, the transmitted and/orreceived currents may be continuously measured by the monitoring system.

As shown in FIG. 5, the transmitted current 300 abruptly increases fromthe initial first magnitude 308 (e.g., the current applied to theconductive components 200, 202 of the route 102, as described above) toa larger second magnitude 500 at a first time 502 within a relativelyshort time period, such as within a few seconds or less than one second.The received current 302 similarly decreases from the initial secondmagnitude 310 (e.g., as described above) to zero current orapproximately zero current within the same relatively short time periodand/or at the same time 502 that the transmitted current abruptlyincreases to the second magnitude 500.

Following the abrupt changes in the transmitted and/or received currents300, 302, the transmitted and received currents remain at orapproximately at the same magnitudes for an extended period of time,such as several minutes, hours, or days. This extended period of timecan be much longer than the time period over which the transmittedand/or received currents increased to the magnitude 400 or decreased tozero (or approximately zero) current. For example, the transmitted andreceived currents can maintain constant or approximately constant valuesfor a time period that is several orders of magnitude longer than thetime period over which the transmitted and/or received currents abruptlychanged. The transmitted and received currents may be “approximately”constant when changes in the currents occur over relatively short timeperiods and are more indicative of noise in the sampling or measurementsof the currents than other causes.

The monitoring system 100 can determine that a foreign object isconnecting the conductive components 200, 202 of the route 102 (asdescribed above) responsive to identifying the abrupt increase in thetransmitted current 300 and/or the abrupt decrease or elimination of thereceived current 302. Additionally or alternatively, the monitoringsystem 100 can determine that the foreign object is connecting theconductive components of the route responsive to (a) identifying theabrupt increase in the transmitted current and/or the abrupt decrease orelimination of the received current, and (b) determining that thetransmitted current remains constant or approximately constant for atleast a threshold, non-zero period of time following the abrupt increaseand/or determining that the received current remains at or approximatelyat zero current for at least the threshold, non-zero period of timefollowing the abrupt decrease. The monitoring system can determine thatthe transmitted and/or receive currents remain constant or approximatelyconstant for at least the threshold, non-zero period of time when thechanges in the currents last for relatively short periods of time and/oroccur at approximately the same or the same time, as is the case for thechanges 504, 506 and the changes 508, 510 shown in FIG. 5.

In one aspect, the monitoring system 100 may detect temporaryfluctuations or changes 504, 506, 508, 510 in the transmitted andreceived currents 300, 302 following the abrupt increase and/or decreasein the transmitted and/or received currents. These changes may be largerthan noise in the currents that are sensed, and may occur over arelatively smaller period of time. For example, the changes may havemagnitudes that are larger than the standard deviation (or anotherstatistical measure or calculation) of the measured current during timeperiods that follow the abrupt increase or decrease in the current.

The monitoring system can determine whether the temporary changes occurat the same or approximately same time. For example, the monitoringsystem can determine that the changes 504, 506 in the transmitted andreceived currents occur at the same or approximately the same time andthat the changes 508, 510 in the transmitted and received currents occurat the same or approximately the same time. When the changes 504, 506and 508, 510 in the transmitted and received currents occur at the sameor approximately same time (e.g., the temporary change in thetransmitted current occurs during a time period that is the same as oroverlaps with a time period during which the temporary change in thereceived current occurs), the monitoring system may confirm that aforeign object is connecting (e.g., shorting out) the conductivecomponents 200, 202 of the route 102. For example, the temporary changesoccurring in the same current may be caused by relatively smallmovements of the foreign object (e.g., vibration of a conductive body onthe tracks due to wind or movement of another nearby vehicle system).Because the same foreign object engages both conductive components tocause the abrupt changes in the transmitted and received currents shownin the example of FIG. 5, temporary movements of the foreign object maybe represented by the temporary changes occurring at the same time orapproximately the same time in the transmitted and received currents.

FIG. 6 illustrates examples of changes in the transmitted current 300that is injected into the conductive components of the route at thetransmitting location 106 along the route 102 and changes in thereceived current 302 that is sensed by the monitoring system at thereceiving location 108 along the route when one or more of theconductive components 200, 202 of the route are damaged or broken. Oneor more of these conductive components can be broken when the conductivecomponent is cut or separated through an entire cross-sectional area ofthe conductive component. For example, a rail of a track is completelybroken when a segment of the rail that previously was a continuous orcontiguous section of the rail is separated into two separate sectionsspaced apart by a gap. A conductive component of the route can bedamaged when the conductive component is cut or separated through part,but less than all, of the entire cross-sectional area of the conductivecomponent. For example, a rail of a track is damaged but not broken whena segment of the rail is partially separated into two separate sections,but is still at least partially connected.

The transmitted and received currents 300, 302 are shown in FIG. 6alongside the horizontal axis 304 and the vertical axis 306 describedabove. The transmitted and received currents may be sampled by themonitoring system at various times, similar to as described above.Alternatively, the transmitted and/or received currents may becontinuously measured by the monitoring system.

As shown in FIG. 6, both of the transmitted and received currents 300,302 abruptly decrease at a time 600. The transmitted current maydecrease from the initial first magnitude 308 (e.g., the current appliedto the conductive components 200, 202 of the route 102, as describedabove) to a smaller second magnitude 602 within a relatively short timeperiod, such as within a few seconds or less than one second. Thereceived current 302 also abruptly decreases from the initial secondmagnitude 310 (e.g., as described above) to zero current orapproximately zero current within the same relatively short time periodand/or at the same time 600. In the illustrated example, the transmittedcurrent decreases to the second magnitude 602 which is larger than theinitial magnitude 310 of the received current, but alternatively maydecrease to a second magnitude that is smaller than the initialmagnitude of the received current. The time 600 may indicate when one ormore of the conductive components were damaged or broken.

Following the abrupt changes in the transmitted and/or received currents300, 302, the transmitted and received currents remain at orapproximately at the same magnitudes for an extended period of time,such as several minutes, hours, or days. This extended period of timecan be much longer than the time period over which the transmittedand/or received currents decreased at the time 600. For example, thetransmitted and received currents can maintain constant or approximatelyconstant values for a time period that is several orders of magnitudelonger than the time period over which the transmitted and/or receivedcurrents abruptly decreased. The transmitted and received currents maybe “approximately” constant when changes in the currents occur overrelatively short time periods and are more indicative of noise in thesampling or measurements of the currents than other causes.

In the illustrated example, the received current 302 is eliminated orsubstantially eliminated at the time 600. For example, following thetime 600, the monitoring system 100 may no longer detect or sense anyreceived current at the receiving location 108 along the route 102 (asshown in FIG. 1). While the monitoring system may detect or sense somecurrent at the receiving location due to noise or hysteresis, themonitoring system may not detect or sense a measurable received current.This lack of detection of the received current following the time 600can indicate that one or more of the conductive components 200, 202 inthe route was damaged or broken at the time 600. For example, themonitoring system may no longer be able to detect the received currentbecause a break in a rail or significant damage to the rail may preventthe received current from being detected in the receiving location 108of the route. Although the monitoring system may be monitoring the routeat plural terminals 212, 214 (shown in FIG. 2), the received currentthat is measured may be a difference between the currents sensed atthese terminals 212, 214 or otherwise indicative of the electric energysensed at these terminals 212, 214 such that the break or damage in oneof the conductive components 200 or 202 causes the received current tobe eliminated, as shown in FIG. 6.

The monitoring system 100 can determine that one or more of theconductive components 200, 202 is broken or damaged responsive toidentifying the abrupt decrease in the transmitted current 300 and/orthe abrupt decrease or elimination in the received current 302 at thesame time 600 or at approximately the same time. Additionally oralternatively, the monitoring system can determine that one or more ofthe conductive components 200, 202 is broken or damaged responsive toidentifying the elimination in the received current 302, regardless ofchanges in the transmitted current 300.

In one aspect, the monitoring system 100 may distinguish between aforeign object being on the route 102 (e.g., described above inconnection with the example shown in FIG. 5) from a break or damage tothe conductive component 200 and/or 202 in the route based on thepresence or absence in the intermittent temporary changes 504, 506, 508,510 in the transmitted and/or received currents 300, 302. For example,if no intermittent and temporary changes are sensed in the transmittedand/or received currents 300, 302, then the monitoring system candetermine that the route has been broken or damaged. If intermittent andtemporary changes occurring at the same or approximately same time inthe transmitted and received currents are sensed, then the monitoringsystem may determine that there is a foreign object on the route.Additionally or alternatively, the monitoring system may distinguishbetween a foreign object on the route and damage or a break in the routebased on whether the transmitted current increases or decreases when thereceived current decreases. If both the transmitted and receivedcurrents decrease at the same time or approximately the same time, thenthe monitoring system may determine that the route is broken or damaged.If the transmitted current increases while the received currentdecreases, the monitoring system may determine that a foreign object ison the route.

The monitoring system 100 may distinguish between (a) contamination ofthe ballast material 112 (shown in FIG. 1 and described above inconnection with the example shown in FIG. 4) and (b) a foreign object onthe route 102 (e.g., described above in connection with the example ofFIG. 5) or damage or a break in the route (e.g., described above inconnection with FIG. 6) based on the trends in the transmitted and/orreceived currents 300, 302. For example, the increases in thetransmitted current and/or the decreases in the received current thatcan occur when the ballast material is contaminated may occur over muchlonger time periods (e.g., days, weeks, months, or years) than theincreases or decreases in the transmitted and/or received currents whena foreign object is on the route and/or the route is broken or damaged.

The monitoring system 100 can distinguish between the presence of thevehicle system 104 (shown in FIG. 1) on the route 102 (described abovein connection with FIG. 3) and contamination of the ballast material 112(described above in connection with FIG. 4) based on the trends in thetransmitted and/or received currents 300, 302. For example, theincreases in the transmitted current and/or the decreases in thereceived current that can occur when the ballast material iscontaminated may occur over much longer time periods (e.g., days, weeks,months, or years) than the increases or decreases in the transmittedand/or received currents when the vehicle system is in the examinedsegment of the route.

The monitoring system 100 can distinguish between the presence of thevehicle system 104 (shown in FIG. 1) on the route 102 (described abovein connection with FIG. 3) and a foreign object being on the route 102(described above in connection with FIG. 5) based on the change in thereceived current 302, the duration of the changes in the transmittedand/or received currents 300, 302, and/or the temporal correlationbetween the temporary changes 504, 506 and 508, 510 (shown in FIG. 5).For example, the received current may not decrease to zero current orapproximately zero current when the vehicle system is detected on theroute, but may decrease to zero current or approximately zero currentwhen the foreign object is on the route. The transmitted and/or receivedcurrents may respectively increase and decrease for a shorter period oftime when the vehicle system is detected on the route than when theforeign object is on the route. For example, the transmitted current mayincrease and the received current may decrease and remain increased ordecreased until the foreign object is removed. The temporary changes inthe transmitted and received currents may not occur at the same orapproximately same times (e.g., which indicates temporal correlationbetween the temporary changes) when the vehicle system is detected onthe route, but may occur when a foreign object is on the route.

The problems or faults that may be identified or predicted by themonitoring system 100 are not limited to those problems or faultsdescribed herein. For example, changes in the transmitted current and/orreceived current may be associated with other faults. Over time,historical changes in the transmitted current and/or received currentcan be associated with various problems or faults with examined segment216 of the route 102. These historical changes can be compared withnewly obtained transmitted currents and/or received currents in order todetermine if the changes in the newly obtained transmitted currentsand/or received currents more closely match one or more of thehistorical changes. If so, then the problems or faults associated withthe historical changes that match the newly obtained currents may beidentified as a problem or fault. For example, additional failures suchas foreign currents interfering with a circuit that includes theconductive components of the route (e.g., currents coming from faults onan adjacent electrified segment of the route, a defective cathodicprotection system on a buried pipeline, or the like), defectiveinsulated joints of the route, or other problems may be identified bycomparing the transmitted currents and/or received currents withhistorical data.

FIG. 7 is another schematic illustration of the monitoring system 100shown in FIG. 1. The example of the monitoring system in FIG. 7 providesadditional details about components that may be included in themonitoring system in one embodiment. The monitoring system includes oris connected with a power source 700, such as one or more utility powergrids, batteries, fuel cells, capacitors, flywheels, generators,alternators, or other sources of electric current. The power sourceprovides electric current that is applied to the conductive components200, 202 of the route 102 in the transmitting location 106 by themonitoring system.

A transmit controller 702 of the monitoring system controls the electriccurrent that is applied to the route by the power source. The transmitcontroller includes or represents hardware circuits or circuitry thatincludes or is connected with one or more processors or other electroniclogic-based devices that operate to perform the functions of thetransmit controller. The transmit controller can control the magnitude(e.g., volts, amps, power, or the like), waveform, frequency, or thelike, of the transmit current supplied from the power source, such as byoperating one or more switches or other devices that are included in orcoupled with the transmit controller.

A transmit monitor 704 of the monitoring system measures the transmittedcurrent that is applied to the route by the power source. The transmitmonitor includes or represents hardware circuits or circuitry thatincludes or is connected with one or more processors or other electroniclogic-based devices that operate to perform the functions of thetransmit monitor. The transmit monitor can be coupled with the route atthe same terminals 208, 210 where the transmit current is applied to theroute, and/or can be coupled with the route in another location in orderto measure the transmit current. In one aspect, the transmit monitor caninclude a voltmeter, amp meter, or combination thereof, that measuresthe transmit current.

A memory 706 of the monitoring system includes one or more devices thatcan store the transmit currents measured by the transmit monitor. Forexample, the memory can include one or more computer hard drives, flashdrives, magnetic tapes, optical discs, or the like. The memory can storethe measured transmit currents over time for analysis or examination.

A communication device 708 of the monitoring system includes transceiverhardware and/or circuitry that includes or is connected with one or moretransceiver devices 710 (e.g., an antenna, modem, or the like) thatcommunicate signals with one or more other communication devices. In theillustrated example, the transceiver device is an antenna thatwirelessly communicates (e.g., transmits, broadcasts, and/or receives)signals. Optionally, the transceiver device may be coupled with one ormore conductive pathways 718 (e.g., cables, catenaries, rails, or thelike) to communicate signals through the conductive pathways.

A sensor 712 of the monitoring system is coupled with the route in thereceiving location 108 to measure the received currents conductedthrough the conductive components of the route. The sensor may includeor represent a voltmeter, amp meter, or combination thereof, thatmeasures the receive current. The sensor can be connected with the routeby the terminals 212, 214.

A receive monitor 714 of the monitoring system measures the receivedcurrent that is conducted through the conductive components of theroute. The receive monitor is connected with the sensor to monitor thereceived current. The receive monitor can include or represent hardwarecircuits or circuitry that includes or is connected with one or moreprocessors or other electronic logic-based devices that operate toperform the functions of the receive monitor.

Another memory 716 of the monitoring system includes one or more devicesthat can store the received currents measured by the receive monitor.For example, the memory can include one or more computer hard drives,flash drives, magnetic tapes, optical discs, or the like. The memory canstore the measured received currents over time for analysis orexamination. In one embodiment, the memories 706, 716 can be combinedinto a single memory.

Another communication device 720 of the monitoring system includestransceiver hardware and/or circuitry that includes or is connected withone or more transceiver devices 722 (e.g., an antenna, modem, or thelike) that communicate signals with one or more other communicationdevices. In the illustrated example, the transceiver device is anantenna that wirelessly communicates (e.g., transmits, broadcasts,and/or receives) signals. Optionally, the transceiver device may becoupled with the one or more conductive pathways 718 (e.g., cables,catenaries, rails, or the like) to communicate signals through theconductive pathways. The communication devices 708, 720 can communicatewith each other so that the transmitted and/or received currents can bestored in one or more of the memories 706, 716, and/or for the transmitmonitor and/or receive monitor to track changes in the transmittedand/or received currents.

The transmit monitor and/or receive monitor can monitor the transmittedand/or received currents as described above in order to determine when avehicle system 104 (shown in FIG. 1) enters into the examined segment216 of the route, when the ballast material 112 (shown in FIG. 1) needsto be cleaned or replaced, when a foreign object is on the route, whenthe route is broken or damaged, and the like. The communication devicescan be used so that the transmit monitor is aware of the receivedcurrents and/or the receive monitor is aware of the transmittedcurrents. Optionally, only one of the transmit monitor or the receivemonitor examines the transmitted and received currents to determine whena vehicle system enters into the examined segment of the route, when theballast material needs to be cleaned or replaced, when a foreign objectis on the route, when the route is broken or damaged, and the like.Additionally or alternatively, one or more of the transmit monitor orthe receive monitor may be disposed at a remote location for remotelyexamining the transmitted and/or received currents as described above inorder to determine when a vehicle system enters into the examinedsegment of the route, when the ballast material needs to be cleaned orreplaced, when a foreign object is on the route, when the route isbroken or damaged, and the like.

In the illustrated example, the examined segment 216 of the route 102 isbetween additional segments 724, 726 of the route. The segments 216,724, 726 are spaced apart from each other by electrically insulativegaps 728. The insulative gaps prevent the conductive components in theneighboring segments of the route from being conductively coupled witheach other. The neighboring segments 724, 726 also may be connected withseparate monitoring systems that are similar to the monitoring system100 described herein. Each of these monitoring systems can examine thetransmitted and/or received currents in order to determine when avehicle system enters into the corresponding segment of the route, whenthe ballast material beneath the corresponding segment of the routeneeds to be cleaned or replaced, when a foreign object is on the routein the corresponding segment, when the corresponding segment of theroute is broken or damaged, and the like, as described above.

In one embodiment, two or more of the monitoring systems that monitordifferent segments of the route can communicate with each other in orderto identify causes of changes in the transmitted and/or receivedcurrents. For example, a first monitoring system that is locatedupstream of a second monitoring system along the route can communicatewith the second monitoring system in order to determine if changes intransmitted and received currents represent the movement of a vehiclesystem along route, a foreign object on the route, damage or a break inthe route, or the like. The monitoring systems can communicate thetransmitted and received currents with each other. If the transmittedand received currents measured by the monitoring systems change in aserial or sequential manner, then the changes in the transmitted andreceived currents may indicate movement of a vehicle system instead ofanother cause.

FIG. 8 illustrates transmitted and received currents 804, 806 that aremeasured by several monitoring systems 100 connected with differentsegments of the same route in accordance with one embodiment. Thecurrents 804, 806 are shown alongside a horizontal axis 800representative of time and vertical axes 802 representative ofmagnitudes of the transmitted and received currents.

The transmitted and received currents 804A, 806A are measured by a firstmonitoring system 100 that is coupled with a first segment of the route102, the transmitted and received currents 804B, 806B are measured by asecond monitoring system 100 that is coupled with a second segment ofthe route 102 located downstream from the first segment along adirection of travel of a vehicle system, the transmitted and receivedcurrents 804C, 806C are measured by a third monitoring system 100 thatis coupled with a third segment of the route 102 located downstream fromthe second segment along a direction of travel of a vehicle system, andthe transmitted and received currents 804D, 806D are measured by afourth monitoring system 100 that is coupled with a fourth segment ofthe route 102 located downstream from the third segment along adirection of travel of a vehicle system. Additional or fewer monitoringsystems and segments may be used.

As a vehicle system 104 travels along the route 102, the monitoringsystems detect changes 808, 810 in the transmitted and received currents804, 806, as described above in connection with FIG. 3. As shown in FIG.8, these changes 808, 810 occur sequentially among the differentsegments and monitoring systems. These sequentially spaced changes 808,810 can indicate that the vehicle system is moving along the route, withthe vehicle system traveling over the first segment during a first timeperiod 812, over the second segment during a second time period 814,over the third segment during a third time period 816, and over thefourth segment during a fourth time period 818.

The monitoring systems can communicate the transmitted and receivedcurrents 804, 806 with each other (and/or another signal that indicatesthe presence of the vehicle system in the segments of the route beingmonitored by the monitoring systems) so that the monitoring systems candistinguish between changes in the transmitted and received currentsthat represent the presence of the vehicle system versus other causes inthe changes. For example, changes in the transmitted and receivedcurrents caused by contaminated ballast material 112 may notsequentially occur among the different segments of the route, changes inthe transmitted and received currents caused by a foreign object on theroute may not sequentially occur among the different segments of theroute, and changes in the transmitted and received currents caused bydamage or a break in the route may not sequentially occur among thedifferent segments of the route. The monitoring systems can communicatewith each other to avoid incorrectly identifying movement of a vehiclesystem with contaminated ballast material, a foreign object on theroute, damage to the route, a break in the route, or the like.

FIGS. 9A and 9B illustrate a flowchart of a method 900 for monitoring asegment of a route in accordance with one embodiment of the inventivesubject matter. The method may be used by the monitoring system 100(shown in FIG. 1) to monitor the examined segment 216 (shown in FIG. 2)of the route 102 (shown in FIG. 1). Although several differentmonitoring methodologies are described and shown herein, the monitoringsystem and method may use several or all of these methodologies at thesame time.

At 902, electric current is applied to conductive components of a routeas a transmitted current. This current can be an alternating current, adirect current, or another type of current. At 904, the transmittedcurrent is monitored. For example, the amps, voltage, frequency, orother characteristic of the transmitted current may be measured orotherwise tracked over time in order to identify changes in thetransmitted current.

At 906, current that is conducted along the conductive components of theroute to a receiving location is monitored as a received current. Forexample, the amps, voltage, frequency, or other characteristic of thetransmitted current may be measured or otherwise tracked over time inorder to identify changes in the received current.

At 908, a determination is made as to whether the transmitted currentincreased and then decreased and/or the received current decreased andthen increased within a relatively short time period. For example, asshown above in the example of FIG. 3, the travel of a vehicle systemalong the examined segment of the route can cause the transmittedcurrent to increase at the same time or approximately the same time thatthe received current decreases, followed by the transmitted currentdecreasing at the same or approximately the same time that the receivedcurrent increases, within a relatively short period of time. In theevent of these changes to the transmitted and received currents, themonitoring system may determine that a vehicle system is located in orhas traveled over the examined segment of the route. As a result, flowof the method 900 continues to 910. On the other hand, if thetransmitted current and/or received current does not change in this way,then the monitoring system may determine that the changes in thetransmitted current and/or received current do not indicate the presenceof a vehicle system in the examined section of the route. As a result,flow of the method 900 proceeds to 912.

At 910, the presence of the vehicle system in the examined segment ofthe route is identified by the monitoring system. The monitoring systemcan report this presence of the vehicle system to one or more otherlocations, such as another monitoring system (as described above), to asignal to warn other vehicle systems of the presence of the vehiclesystem on the examined segment of the route, or the like. At 924, themonitoring system can take one or more remedial or responsive actions,such as reporting the presence of the vehicle system to anotherlocation.

At 912, a determination is made as to whether the transmitted currentincreases and the received current decreases for an extended period oftime, and/or if intermittent temporary changes in the transmittedcurrent are temporally correlated with similar changes in the receivedcurrent. For example, as described above in connection with the exampleof FIG. 5, the monitoring system may determine if the transmittedcurrent increases and the received current decreases (or issubstantially eliminated) at the same time or approximately the sametime. The monitoring system also may determine if temporary changes 504,506, 508, 510 in the transmitted and received currents occur at the sametime or approximately the same time. If the monitoring system identifiessuch changes in the transmitted and received currents, the changes mayindicate a foreign object is connected to the conductive components ofthe route and may be shorting out the circuit that includes theconductive components. As a result, flow of the method 900 may proceedto 914. Otherwise, the changes in the currents may not indicate thepresence of a foreign object, and flow of the method 900 can proceed to916.

At 914, a foreign object is identified as connecting the conductivecomponents of the route by the monitoring system. At 924, the monitoringsystem can take one or more remedial or responsive actions, such asreporting the presence of the foreign object to another location toschedule or request that an operator or maintainer travel to thelocation of the examined segment of the route to remove the foreignobject. Optionally, the monitoring system can communicate a signal toother vehicle systems or signals to warn the vehicle systems or changethe status of the signal to prevent travel of the vehicle systems ontothe examined segment of the route.

At 916, a determination is made as to whether the transmitted currentand the received current decrease. For example, the monitoring systemmay determine whether the transmitted current decreases and the receivedcurrent decreases (or is eliminated) at the same time or approximatelythe same time. These changes in the transmitted current and receivedcurrent may indicate that the route is damaged or broken within theexamined segment, as described above in connection with FIG. 6. In oneaspect, the monitoring system may determine if the transmitted currentdecreases and the received current reduces to zero (or approximatelyzero) current for an extended period of time, such as several minutes orhours. If the monitoring system identifies these changes in thetransmitted and/or received currents, the monitoring system candetermine that the route has been damaged or broken. As a result, flowof the method 900 may proceed to 918. On the other hand, if thesechanges are not identified, then the transmitted currents and receivedcurrents may not indicate that the route is damaged or broken. As aresult, flow of the method 900 can proceed to 920.

At 918, the examined segment of the route is identified as being brokenor damaged, as described above, by the monitoring system. At 924, themonitoring system can take one or more remedial or responsive actions,such as reporting the damage or break in the route to another locationto schedule or request that an operator or maintainer travel to thelocation of the examined segment of the route to repair or examine theroute. Optionally, the monitoring system can communicate a signal toother vehicle systems or signals to warn the vehicle systems or changethe status of the signal to prevent travel of the vehicle systems ontothe examined segment of the route.

At 920, a determination is made as to whether the transmitted currentdemonstrates an increasing trend and/or the received currentdemonstrates a decreasing trend over an extended period of time. Forexample, the monitoring system can examine the transmitted currentand/or the received current over one or more hours, days, weeks, months,or years in order to determine if the transmitted current is graduallyincreasing while the received current also is gradually decreasing. Ifthe transmitted current is exhibiting such an increasing trend and/orthe receiving current is exhibiting such a decreasing trend over anextended time period, then these trends in the transmitted and receivedcurrents may indicate that the ballast material beneath the conductivecomponents of the route is forming a short or shunt that is at leastpartially conducting current between the conductive components. As aresult, flow of the method 900 can proceed to 922. On the other hand, ifthe transmitted current is not exhibiting such an increasing trendand/or the received current is not exhibiting such a decreasing trend,then the transmitted and received currents may not indicate that theballast material is forming a short or shunt. As a result, flow of themethod 900 can return to 902.

At 922, the monitoring system can identify the ballast material as beingcontaminated in that the ballast material is at least partiallyconducting current between the conductive components of the route. At924, the monitoring system can take one or more remedial or responsiveactions, such as reporting the contaminated portion of the ballastmaterial to another location to schedule or request that an operator ormaintainer travel to the location of the examined segment of the routeto replace, clean, or otherwise repair the ballast material. Optionally,the monitoring system can communicate a signal to other vehicle systemsor signals to warn the vehicle systems or change the status of thesignal to prevent travel of the vehicle systems onto the examinedsegment of the route. In one aspect, the monitoring system cancommunicate a request to an off-board location that the examined segmentof the route be repaired, such as by adding a resistive element (e.g.,one or more resistors), in order to change the electric characteristicsof the circuit that includes the conductive components of the route inthe examined segment of the route. Adding such a resistive element canreduce or eliminate the increasing trend in the transmitted currentand/or the decreasing trend in the received current.

In one embodiment, a wayside monitoring method includes monitoring atransmitted current that is injected into conductive components of aroute that is traveled by one or more vehicle systems, monitoring areceived current that represents at least a portion of the transmittedcurrent that is conducted through the conductive components of theroute, examining changes in one or more of the transmitted current orthe received current over time to determine when at least one of thevehicle systems is disposed on the route between a first location alongthe route where the transmitted current is injected into the conductivecomponents and a different, second location along the route where thereceived current is monitored, and examining the same changes in the oneor more of the transmitted current or the received current to identifyat least one of a contaminated portion of a surface on which theconductive components of the route are disposed, to identify a foreignobject other than the one or more vehicle systems that is contacting theconductive components of the route, or to identify a damaged or brokenportion of at least one of the conductive components of the route.

In one aspect, the changes that are examined to both determine when atleast one of the vehicles is disposed on the route and to identify theat least one of the contaminated portion, the foreign object, or thedamaged or broken portion of the at least one of the conductivecomponents of the route include increases or decreases in thetransmitted current and the received current and time periods over whichthe increases or decreases in the transmitted current and the receivedcurrent occur.

In one aspect, the contaminated portion of the surface includes aportion of ballast material disposed beneath the conductive componentsof the route that at least partially conducts the transmitted currentbetween the conductive components of the route through the contaminatedportion of the surface.

In one aspect, the foreign object that is identified is one or moreconductive bodies forming a short between the conductive components ofthe route.

In one aspect, the damaged or broken portion of the at least one of theconductive components of the route includes a portion of the at leastone of the conductive components that is separated through an entirecross-sectional area of the at least one of the conductive components.

In one aspect, the contaminated portion of the surface on which theconductive components of the route are disposed is identified when thechanges in the transmitted current and in the received current includean increasing trend in the transmitted current over an extended periodof time that concurrently occurs with a decreasing trend in the receivedcurrent over the extended period of time.

In one aspect, the foreign object is identified when the changes in thereceived current include a decrease in the received current to zerocurrent or approximately zero current and temporary changes in thereceived current that are temporally correlated with temporary changesin the transmitted current.

In one aspect, the damaged or broken portion of the at least one of theconductive components of the route is identified when the changes in thetransmitted current and in the received current include a decrease inthe transmitted current that occurs concurrently with an elimination ofthe received current.

In one aspect, the route includes a track over which rail vehiclestravel and the conductive components include rails of the track.

In another embodiment, a wayside monitoring system includes a transmitmonitor and a receive monitor. The transmit monitor includes one or moreprocessors configured to measure a transmitted current that is injectedinto conductive components of a route that is traveled by one or morevehicle systems. The receive monitor includes one or more processors(which may be one or more of the same processors as the transmit monitoror different processors than the transmit monitor) that are configuredto measure a received current that represents at least a portion of thetransmitted current that is conducted through the conductive componentsof the route. At least one of the transmit monitor or the receivemonitor also is configured to examine changes in one or more of thetransmitted current or the received current over time to determine whenat least one of the vehicle systems is disposed on the route between afirst location along the route where the transmitted current is injectedinto the conductive components and a different, second location alongthe route where the received current is monitored. At least one of thetransmit monitor or the receive monitor is configured to examine thesame changes in the one or more of the transmitted current or thereceived current to identify at least one of a contaminated portion of asurface on which the conductive components of the route are disposed, toidentify a foreign object other than the one or more vehicle systemsthat is contacting the conductive components of the route, or toidentify a damaged or broken portion of at least one of the conductivecomponents of the route.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to examine the changes in the transmitted currentand in the received current to both determine when at least one of thevehicles is disposed on the route and to identify the at least one ofthe contaminated portion, the foreign object, or the damaged or brokenportion by identifying: (a) increases or decreases in the transmittedcurrent and the received current and (b) time periods over which theincreases or decreases in the transmitted current and the receivedcurrent occur.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to identify the contaminated portion of thesurface as a portion of ballast material disposed beneath the conductivecomponents of the route that at least partially conducts the transmittedcurrent between the conductive components of the route through thecontaminated portion of the surface.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to identify the foreign object as one or moreconductive bodies forming a short between the conductive components ofthe route.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to identify the damaged or broken portion of theat least one of the conductive components of the route as a portion ofthe at least one of the conductive components that is separated throughan entire cross-sectional area of the at least one of the conductivecomponents.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to identify the contaminated portion of thesurface responsive to the changes in the transmitted current and in thereceived current including an increasing trend in the transmittedcurrent over an extended period of time that concurrently occurs with adecreasing trend in the received current over the extended period oftime.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to identify the foreign object responsive to thechanges in the received current including a decrease in the receivedcurrent to zero current or approximately zero current and temporarychanges in the received current being temporally correlated withtemporary changes in the transmitted current.

In one aspect, at least one of the transmit monitor or the receivemonitor is configured to identify the damaged or broken portion of theat least one of the conductive components of the route is identifiedresponsive to the changes in the transmitted current and in the receivedcurrent including a decrease in the transmitted current that occursconcurrently with an elimination of the received current.

In one aspect, the route includes a track over which rail vehiclestravel and the conductive components include rails of the track.

In another embodiment, a wayside monitoring method includes measuring atransmitted current that is applied to a conductive rail of a track overwhich one or more rail vehicles travel at a first location and measuringa received current at a different, second location to the conductiverails of the track. The received current includes at least a portion ofthe transmitted current that is conducted through one or more of theconductive rails from the first location to the second location. Themethod also can include identifying changes in the transmitted currentand in the received current over time in order to both identify when theone or more of the rail vehicles travel between the first location andthe second location and when at least one of: ballast material disposedbetween the conductive rails becomes contaminated to at least partiallyform a short between the conductive rails, a foreign object other thanthe one or more rail vehicles forms the short between the conductiverails, or one or more of the conductive rails is damaged or brokenbetween the first location and the second location.

In one aspect, the changes in the transmitted current and the changes inthe received current indicate that the ballast material is contaminatedwhen the transmitted current increases and the received currentdecreases over an extended period of time that is longer than a timeperiod during which the one or more rail vehicles travel over theconductive rails between the first location and the second location at atrack speed of the conductive rails.

In one aspect, the changes in the transmitted current and the changes inthe received current indicate that the foreign object is forming theshort between the conductive rails responsive to the transmitted currentincreasing and the received current concurrently decreasing, followed byone or more temporary changes in the transmitted current and one or moretemporary changes in the received current occurring during common timeperiods.

In one aspect, the changes in the transmitted current and the changes inthe received current indicate that one or more of the conductive railsis damaged or broken when the transmitted current decreases and thereceived current is concurrently eliminated.

FIG. 10 is a schematic diagram of another monitoring system 1000. Themonitoring system 1000 includes or represents one or more hardwarecircuits or circuitry that includes and/or is coupled with one or moreprocessors, controllers, or other electronic logic-based devices thatoperate to perform various operations described herein. The monitoringsystem 1000 is coupled with the route 102 on which the vehicle systems104 travel along.

In contrast to the monitoring system 100 shown in FIG. 7, the monitoringsystem 1000 can include an off-board assembly 1001 and an onboardassembly 1003. The off-board assembly 1001 is located off-board thevehicles and vehicle systems, while the onboard assembly 1003 is onboardat least one of the vehicles or vehicle systems. During operation, theonboard assembly 1003 may move relative to the off-board assembly 1001,as described herein.

The off-board assembly 1001 of the monitoring system 1000 is coupledwith the route 102. For example, the off-board assembly 1001 can bestationary and connected with the route 102 at the single location 108but not the location 106. The off-board assembly 1001 is not connectedwith either of the conductive portions 200, 202 at multiple locationsthat are spaced apart from each other along the length of the portion200 or the portion 202. For example, the off-board assembly 1001 caninclude the terminals 208, 210 that are affixed or otherwise connectedin fixed locations to the conductive portions 200, 202 of the route 102.

The onboard assembly 1003 of the monitoring system 1000 engages theroute 102 at locations that change as the vehicle or vehicle system onwhich the onboard assembly 1003 is disposed moves along the route 102.For example, the onboard assembly 1003 can include contact bodies 1008,1010 that engage the conductive portions 200, 202 of the route 102 whilethe vehicle on which the onboard assembly 1003 is disposed moves alongthe conductive portions 200, 202. These contact bodies 1008, 1010 caninclude conductive shoes, brushes, plates, or the like, that can touchthe portions 200, 202 during movement. Optionally, the contact bodies1008, 1010 can be inductive contact bodies (e.g., conductive coils) thatare inductively coupled with the portions 200, 202 of the route 102without contacting the route 102. The contact bodies 1008, 1010 caninject the transmitted current into the portions 200, 202 of the route102 during movement, as described above in connection with thetransmitted current being injected into the route 102 at the terminals208, 210.

In the illustrated embodiment, off-board assembly 1001 includes thesensor 712, the receive monitor 714, optionally the memory 716, andoptionally the communication device 720 (with the antenna 722). Thesecomponents may remain stationary while the onboard assembly 1003 movesalong the route 102. The onboard assembly 1003 includes the transmitcontroller 702, the transmit monitor 704, optionally the memory 706, andoptionally the communication device 708 (with associated antenna 710).The onboard assembly 1001 also includes a power source 1005 such as oneor more batteries, fuel cells, capacitors, flywheels, generators,alternators, or other sources of electric current. Alternatively, thepower source 1005 can represent a stationary power source, such as acatenary or electrified rail. The power source 1005 provides electriccurrent that is applied to the conductive components 200, 202 of theroute 102 by the conductive bodies 1008, 1010.

The monitoring system 1000 may be coupled with the route 102 (a) at themoving interfaces between the conductive bodies 1008, 1010 and theconductive portions 200, 202 of the route 102 and (b) at the fixedinterfaces or connections between the terminals 212, 214 and theconductive portions 200, 202 of the route 102 so that the monitoringsystem can inject electric signals (e.g., electric currents that arecontrolled by the monitoring system) into the route at a movingtransmitting location 1006 (e.g., the moving interfaces between theconductive bodies 1008, 1010 and the conductive portions 200, 202 of theroute 102), as described above. The monitoring system 1000 can receiveelectric signals (e.g., the electric current that is injected into theroute at the transmitting location and that is conducted along theroute) at the receiving location 108.

As described above, the monitoring system injects the electric signalsinto the route at the transmitting location 106 by applying thetransmitting or transmitted current that is controlled by the monitoringsystem to the route. The monitoring system can measure the electriccurrent that is conducted along the route at the receiving location 108.Based on changes in the transmitted current, changes in the receivedcurrent, and/or differences between the transmitted and receivedcurrents, the monitoring system can track changes in the transmittedcurrent and/or changes in the received current over time in order toidentify and/or predict damage to the route, as described above.

The communication device 708 of the onboard assembly 1003 cancommunicate a notification signal (e.g., via the antennas 710, 722) tothe communication device 720 of the off-board assembly 1001 to notifythe off-board assembly 1003 when the onboard assembly 1003 isapproaching the location 108 associated with the off-board assembly1001. This can ensure that the onboard assembly 1003 injects thetransmitted current into the route 102 once the transmitting location1006 is within a designated distance from the receiving location 108(e.g., to prevent dissipation of the current from being erroneouslyinterpreted by the receive monitor 714 as a broken rail, damaged rail,or contaminated ballast when the rail is not broken, the rail is notdamaged, or the ballast is not contaminated. Optionally, thecommunication device 720 of the off-board assembly 1001 can communicatea notification signal (e.g., via the antennas 710, 722) to thecommunication device 708 of the onboard assembly 1003 to notify theonboard assembly 1001 when the onboard assembly 1003 is approaching thelocation 108 associated with the off-board assembly 1001. This canensure that the onboard assembly 1003 injects the transmitted currentinto the route 102 once the transmitting location 1006 is within thedesignated distance from the receiving location 108. For example, thecommunication device 720 can operate as a beacon that repeatedlybroadcasts a wireless signal to notify the onboard assembly 1003 of theapproach of the onboard assembly 1003 to the off-board assembly 1001.

The receive monitor 714 can obtain several samples of the receivedcurrent over an extended period of time to monitor the route 102 and/orballast condition, as described above. The received currents that aresampled can be based on transmitted current injected into the route 102by the same onboard assembly 1003 on the same vehicle or vehicle systemand/or by several onboard assemblies 1003 onboard different vehicles orvehicle systems. For example, each time or multiple (but not each) timesthat a vehicle having the onboard assembly 1003 comes near the receivinglocation 108 of the off-board assembly 1001, the off-board assembly 1001can sample the current injected into the route 102 by the onboardassembly 1003. These samples can be examined to identify changes incharacteristics of the route and/or ballast over time, as describedabove. Responsive to identifying a problem with the route or ballast,the communication device 720 can communicate warning signals to thecommunication devices 708 of vehicles and/or to a facility (e.g., ascheduling or dispatch facility) to warn the vehicles of the problem.The vehicles can then change which route the vehicles travel on and/orthe facility can change the state of signals, switches, or the like, tocause the vehicles to travel around, and not over, the location of theproblem with the route or ballast.

Alternatively, the sensor 712, receive monitor 714, memory 716, and/orcommunication device 722 may be disposed onboard a vehicle system whilethe power source 1005, transmit controller 702, transmit monitor 704,memory 706, and/or communication device 708 are off-board the vehiclesystem. The sensor 712 can be coupled with the route 102 by theterminals 212, 214 being conductive shoes, conductive brushes,conductive plates, or the like, that contact the conductive portions200, 202 of the route 102 or inductive coils that are inductivelycoupled with the conductive portions 200, 202 of the route 102. Thisinterface between the sensor 712 and the route 102 may move along theroute 102 while the transmit monitor 704 injects the current into theroute 102 via the terminals 1006, 1008, which are fixed in position.

It is to be understood that the above description is intended to beillustrative, and not restrictive. For example, the above-describedembodiments (and/or aspects thereof) may be used in combination witheach other. In addition, many modifications may be made to adapt aparticular situation or material to the teachings of the inventivesubject matter without departing from its scope. While the dimensionsand types of materials described herein are intended to define theparameters of the inventive subject matter, they are by no meanslimiting and are exemplary embodiments. Many other embodiments will beapparent to one of ordinary skill in the art upon reviewing the abovedescription. The scope of the inventive subject matter should,therefore, be determined with reference to the appended claims, alongwith the full scope of equivalents to which such claims are entitled. Inthe appended claims, the terms “including” and “in which” are used asthe plain-English equivalents of the respective terms “comprising” and“wherein.” Moreover, in the following claims, the terms “first,”“second,” and “third,” etc. are used merely as labels, and are notintended to impose numerical requirements on their objects. Further, thelimitations of the following claims are not written inmeans-plus-function format and are not intended to be interpreted basedon 35 U.S.C. § 112(f), unless and until such claim limitations expresslyuse the phrase “means for” followed by a statement of function void offurther structure.

This written description uses examples to disclose several embodimentsof the inventive subject matter and also to enable one of ordinary skillin the art to practice the embodiments of inventive subject matter,including making and using any devices or systems and performing anyincorporated methods. The patentable scope of the inventive subjectmatter is defined by the claims, and may include other examples thatoccur to one of ordinary skill in the art. Such other examples areintended to be within the scope of the claims if they have structuralelements that do not differ from the literal language of the claims, orif they include equivalent structural elements with insubstantialdifferences from the literal languages of the claims.

The foregoing description of certain embodiments of the presentinventive subject matter will be better understood when read inconjunction with the appended drawings. To the extent that the figuresillustrate diagrams of the functional blocks of various embodiments, thefunctional blocks are not necessarily indicative of the division betweenhardware circuitry. Thus, for example, one or more of the functionalblocks (for example, processors or memories) may be implemented in asingle piece of hardware (for example, a general purpose signalprocessor, microcontroller, random access memory, hard disk, and thelike). Similarly, the programs may be stand-alone programs, may beincorporated as subroutines in an operating system, may be functions inan installed software package, and the like. The various embodiments arenot limited to the arrangements and instrumentality shown in thedrawings.

As used herein, an element or step recited in the singular and proceededwith the word “a” or “an” should be understood as not excluding pluralof said elements or steps, unless such exclusion is explicitly stated.Furthermore, references to “one embodiment” of the present inventivesubject matter are not intended to be interpreted as excluding theexistence of additional embodiments that also incorporate the recitedfeatures. Moreover, unless explicitly stated to the contrary,embodiments “comprising,” “including,” or “having” an element or aplurality of elements having a particular property may includeadditional such elements not having that property.

What is claimed is:
 1. A monitoring system comprising: a transmitmonitor configured to be disposed onboard a first vehicle system movingalong a route, the transmit monitor including one or more firstprocessors configured to control injection of a transmitted current intoone or more conductive components of the route; and a receive monitorconfigured to be disposed off-board the first vehicle system, thereceive monitor including one or more second processors configured tomeasure a received current that represents at least a portion of thetransmitted current that is conducted through the one or more conductivecomponents of the route, wherein the transmitted current and thereceived current are injected and received, respectively, at differentspaced-apart locations along the one or more conductive components ofthe route while the transmit monitor moves relative to the receivemonitor; wherein the receive monitor is configured to generate sampledvalues of the measured received current by sampling the measuredreceived current at plural different points in time during which pluralvehicle systems that include the first vehicle system travel over theroute plural times; and wherein the receive monitor is configured toexamine changes in the sampled values to identify a contaminated portionof a surface on which the one or more conductive components of the routeare disposed.
 2. The system of claim 1, wherein the receive monitor isconfigured to examine the changes in the sampled values by identifying:increases or decreases in the sampled values; and time periods overwhich the increases or decreases in the sampled values occur.
 3. Thesystem of claim 1, wherein the receive monitor is configured to identifythe contaminated portion of the surface as a portion of ballast materialdisposed beneath the one or more conductive components of the route thatat least partially conducts the transmitted current between the one ormore conductive components of the route through the contaminated portionof the surface.
 4. The system of claim 1, wherein the transmit monitoris a first transmit monitor of multiple transmit monitors, and whereinthe receive monitor is configured to measure the received currentmultiple different times that correspond to multiple injections of thetransmitted current by the multiple transmit monitors.
 5. The system ofclaim 1, wherein the receive monitor is configured to identify thecontaminated portion of the surface responsive to the changes in thesampled values including an increasing trend in the transmitted currentover an extended period of time that concurrently occurs with adecreasing trend in the received current.
 6. The system of claim 1,wherein the receive monitor also is configured to identify a foreignobject on the route based on the changes in the sampled values.
 7. Thesystem of claim 1, wherein the receive monitor also is configured toidentify a damaged or broken portion of at least one of the one or moreconductive components of the route based on the changes in the sampledvalues.
 8. A monitoring system comprising: a sensor configured to beaffixed to a conductive portion of a route along which vehicle systemsmove, the sensor configured to measure samples of an electric currentthat is injected into and at least partially conducted through theconductive portion of the route by a transmit controller disposedonboard at least one of the vehicle systems as the at least one vehiclesystem moves along the route; and a receive monitor having one or moreprocessors that are communicatively coupled with the sensor to receivethe samples of the electric current; wherein the sensor is configured tomeasure the samples of the electric current plural different timesspanning a time period that encompasses the vehicle systems travelingover the route several times; and wherein the one or more processors areconfigured to identify a contaminated portion of a surface on which theroute is disposed based on changes in the samples of the electriccurrent over the time period.
 9. The system of claim 8, wherein thesensor is configured to measure the samples of the electric current froma fixed position along the route while the transmit controller injectsthe electric current into the route from a moving position.
 10. Thesystem of claim 8, wherein the one or more processors are configured toidentify the contaminated portion of the surface as a portion of ballastmaterial disposed beneath the route that at least partially conducts theelectric current.
 11. The system of claim 8, wherein the sensor isconfigured to measure the samples of the electric current multipledifferent times that correspond to multiple injections of the electriccurrent by the transmit controllers disposed onboard the vehiclesystems.
 12. The system of claim 8, wherein the one or more processorsare configured to identify the contaminated portion of the surfaceresponsive to the changes in the samples including an increasing trendin the samples over an extended period of time that concurrently occurswith a decreasing trend in the samples.
 13. The system of claim 8,wherein the one or more processors also are configured to identify aforeign object on the route based on the changes in the samples.
 14. Thesystem of claim 8, wherein the one or more processors also areconfigured to identify a damaged or broken portion of the conductivecomponent of the route based on the changes in the samples.
 15. Thesystem of claim 8, further comprising: a communication device operablycoupled with the receive monitor, the communication device configured toone or more of: notify one or more of the vehicle systems that the oneor more vehicle systems are approaching a location of the sensor bycommunicating a first notification signal to the one or more vehiclesystems; or receive a second notification signal from the one or morevehicle systems notifying the receive monitor that the one or morevehicle systems are approaching the location of the sensor.
 16. A methodcomprising: measuring samples of electric current that is injected intoand at least partially conducted through a conductive portion of a routeby a transmit controller disposed onboard one or more vehicle systems asthe one or more vehicle systems move along the route, the samples of theelectric current measured at a fixed location on the route and measuredat different times spanning a time period that encompasses the one ormore vehicle systems traveling over the route several times; andidentifying a contaminated portion of a surface on which the route isdisposed based on changes in the samples of the electric current overthe time period.
 17. The method of claim 16, wherein the contaminatedportion of the surface is identified as a portion of ballast materialdisposed beneath the route that at least partially conducts the electriccurrent.
 18. The method of claim 16, wherein the contaminated portion ofthe surface is identified responsive to the changes in the samplesincluding an increasing trend in the samples over an extended period oftime that concurrently occurs with a decreasing trend in the samples.19. The method of claim 16, further comprising one or more of:identifying a foreign object on the route based on the changes in thesamples; or identifying a damaged or broken portion of the one or moreconductive components of the route based on the changes in the samples.20. The method of claim 16, further comprising one or more of: notifyingone or more of the vehicle systems that the one or more vehicle systemsare approaching the fixed location by communicating a first notificationsignal to the one or more vehicle systems; or receiving a secondnotification signal from the one or more vehicle systems notifying thatthe one or more vehicle systems are approaching the fixed location,wherein at least one of the samples is measured responsive to receivingthe second notification signal.